Conventionally, a high pressure discharge lamp lighting apparatus having a high pressure discharge lamp in which 0.20 mg/mm3 of mercury is enclosed and the pressure thereof at time of lighting becomes 200 atmospheric pressure or more, and a power supply apparatus therefor, is known. In such a high pressure discharge lamp lighting apparatus, during a lighting operation, a projection is formed at the tip of an electrode(s) of a high pressure discharge lamp by a special lighting method, so that arc discharge is stabilized with this projection which serves as a starting point, thereby preventing generation of a flicker. This special lighting method is described in Japanese Patent Application Publication No. 2006-59790, wherein alternating current with a frequency selected from a range of 60-1,000 Hz as a steady state lighting frequency is supplied to such a high pressure discharge lamp, and when frequency of alternating current which is lower than the steady state lighting frequency and is selected from a range of 5-200 Hz, is called a low frequency, the alternating current with the low frequency, in which a length thereof is a half cycle or more to five or less cycle, is inserted in the alternating current of the steady state lighting frequency at an interval selected from a range of 0.01-120 seconds, so that the alternating current of the steady state lighting frequency and the alternating current of the low frequency are applied by turns so as to turn on the lamp.
In many of projector apparatuses using such a high pressure discharge lamp lighting apparatus, a user can arbitrarily switch between a normal mode which turns on a lamp with rated power, and an economic mode in which an operation is performed with lower electric power. Electric power in a conventional economic mode is generally about 80% of electric power in the normal mode. Furthermore, in recent years, there are use needs of a super economic mode in which an operation is performed at 80% or less of electric power in the normal mode, for example, 60%-40%, or a brightness adjustment mode using a timing function in which an input electric power to a lamp is controlled so as to be low, according to a screen, in order to raise a contrast ratio.
In recent years, a high pressure discharge lamp lighting apparatus generally has both the “normal mode” and “economic mode.” Therefore, in the present specification, a lighting operation in which a lamp is turned on in the “normal mode” and “economic mode” is referred to as a steady state lighting (operation). Moreover, since electric power in the “super economic mode” is smaller than that in the steady state lighting, and also the electric power in the “brightness adjustment mode” becomes smaller than that at time of the steady state lighting, a lighting operation in which a lamp is turned on in the “super economic mode” and the “brightness adjustment mode” is hereinafter referred to as a small electric power lighting.